"They called me up and said, 'Do you wanna do this?' And I thought, 'Well, I'm not 25, man. Are you sure about this?' " Affleck told host Jimmy Fallon. It wasn't until after he saw director Zack Snyder's take on the character, a different (albeit "brilliant") version than the one in Christopher Nolan and Christian Bale's Dark Knight trilogy, that he agreed.

After he committed, Affleck recalled conversations he had with the studio about the type of hoopla a key casting like this could create. " 'Listen, we want to talk to you because people go through this process and it can be trying,' " Affleck relayed. "I said, 'What do you mean?' 'We want to show you some of the reactions that past people who have been cast have gotten, like on the Internet and stuff.' "

Though he wouldn't name names, Affleck noted that they were people who were received negatively prior to their movies being filmed. "They send me [reactions for] people who were in these movies who did a great job and they'd say, 'Kill himmmm!' " Affleck said. "You can't say that before a movie comes out. It doesn't matter what you think then, it matters what you think when you see the movie."

But Affleck was sure he could handle the backlash when the announcement hit. "I'm a big boy," he joked. "They said just don't use the Internet for a couple of days.... I handle shit. I'm very tough. I saw the announcement, I look down on the first comment...the first one just goes, 'Nooooooooo!' "

He joked: "We're gonna be Luddites for a while, kids."

Affleck was announced as Batman on Aug. 22, and reactions to his casting in the upcoming Warner Bros. feature -- slated for a July 17, 2015, release -- ran the gamut from excitement ("WTF! Ben Affleck is Batman?! That's genius," actor Josh Gad tweeted) to poking fun ("Really looking forward to seeing Affleck bring the depth and gravitas to Batman that he brought to Daredevil and Gigli," actor Wil Wheaton tweeted).